1. Field of the Invention
The present invention relates to a microcapsule that contains a core material and a method for producing the same. More particularly, the present invention relates to a microcapsule, which has a capsule wall composed of organopolysiloxane obtained by polycondensation of a specific hydroxysilane, having thermal and mechanical stability and light resistance and which is bio-inactive.
The microcapsule of the present invention is applied, for example, to pharmaceuticals, liquid crystal, chemical products, recording materials, cosmetic compositions, aromatics, enzymes, agriculture, adhesives, fiber, foods, catalysts, detergents, dyes, paints, preservatives, solvents and the like. Specific examples thereof include microcapsules containing aspirin, vitamins or liquid crystals, pressure sensitive manifold paper, a capsule containing ultraviolet ray absorbers, coloring matters, pigments, aromatics, menthol, insecticides or adhesives, a capsule containing a preservative for rivet, and the like, although use of the microcapsule is not limited to the above-mentioned uses.
2. Description of the Related Art
Application of organopolysiloxanes in a wide range of fields is expected since they have excellent properties such as thermal and mechanical stability and light resistance, and bio-inactivity and the like as general basic properties. Also in the field of microcapsules, such as a microcapsule in the narrow sense and a nanocapsule, production of microcapsules has been previously tried using a capsule walls composed of a polysiloxane or an analogous material.
For example, U.S. Pat. No. 3,257,330 discloses a method for producing a colored gel particle comprising organopolysiloxane as a matrix. However, when an alkoxysilane having a hydrophobic organic group, such as methyltriethoxysilane and the like, is used as a starting material of the matrix, is hydrolyzed and then neutralized, the polymer composition forms a deposit in an aqueous solution. As a result, it has been difficult to produce a microcapsule by incorporating a hydrophobic core material with the polymerization of a hydrolyzate of an alkoxysilane in the aqueous solution.
On the other hand, U.S. Pat. No. 3,551,346 teaches a method in which a polysiloxane is synthesized from a trialkoxysilane in the production of a microcapsule. However, the polysiloxane does not have sufficient strength as a capsule wall (as admited by this U.S. patent). Therefore, this U.S. patent discloses a method for producing a microcapsule having a capsule wall of a two-layer structure by further making simultaneously a capsule wall by a conventional coacervation method. In addition, it is believed that any more than a certain amount a trialkoxysilane can not be used for producing a capsule wall since the trialkoxysilane is confined in an inner phase by the newly generated polysiloxane capsule wall. Therefore, this method is not admitted as a general method for producing a microcapsule composed only of the polysiloxane capsule wall.
Further, JP-B-60-25185, JP-B-3-10309, JP-B-5-70496, JP-B-7-62109, etc. disclose examples wherein a wall of a microcapsule is produced by cross-linking a polysiloxane having a functional group which can participate in cross-linking and polymerization. However, it is difficult to handle such a specific polysiloxane having a functional group participating in cross-linking and polymerization.
As described above, it has been difficult to easily produce a microcapsule having a capsule wall composed of organopolysiloxane according to conventional technologies.
It is advantageous also in cost to directly produce a microcapsule by making, from a hydroxysilane precursor having various properties, an organopolysiloxane capsule wall that can utilize such properties. Further, microcapsules suited for an object can be easily designed by combining various hydroxysilane precursors. For example, they can be expected to produce various capsule walls such as a capsule wall having tight compact network, a capsule wall having an appropriate permeation property, or a capsule wall having high strength or being suitably soft. However, it has been difficult to produce a microcapsule while controlling conditions such as polymerization rate, solubility and the like when solely using a hydroxysilane precursor having a low molecular weight.
An object of the present invention is to provide a microcapsule that contains a core material, wherein the microcapsule contains a capsule wall composed of organopolysiloxane having excellent properties. Another object of the present invention is to provide a method for producing such a microcapsule easily and with high productivity from generally available silicon compounds.
The present inventors have intensively studied a method for producing a microcapsule having a capsule wall composed of organopolysiloxane directly from a hydroxysilane precursor in order to solve the above-described problems. As a result, the inventors have found that the above-described object can be attained if:
one or more compounds (A) selected from the group of compounds represented by the following general formula (I) are hydrolyzed to produce one or more compounds (B) selected from the group of compounds represented by the following general formula (II):
RnSiX(4xe2x88x92n)xe2x80x83xe2x80x83Formula (I)
wherein, n represents an integer from 0 to 3; R represents an organic group in which a carbon atom is directly connected to a silicone atom, and when n is greater than 1, each of the R groups may be the same or different; and X represents at least one group selected from the group consisting of a hydroxyl group, hydrogen, alkoxy group, halogen group, carboxyl group, amino group and siloxy group, and when (4xe2x88x92n) is greater than 1, each of the groups X may be the same or different; and
RnSi(OH)mY(4xe2x88x92mxe2x88x92n)xe2x80x83xe2x80x83Formula (II)
wherein, m represents an integer from 1 to 4; n represents an integer from 0 to 3; m+nxe2x89xa64; R represents an organic group in which a carbon atom is directly connected to a silicone atom, and when n is greater than 1, each of the R groups may be the same or different; and Y represents at least one group selected from the group consisting of an alkoxy group, hydrogen and siloxy group, and when (4xe2x88x92mxe2x88x92n) is greater than 1, each of the groups Y may be the same or different; provided that the compound (B) comprises at least one compound of formula(II) wherein m=2 or 3 and at least one of R group possesses affinity for at least one of a continuous phase and a dispersed phase; and the compound (B) is polycondensed to synthesize organopolysiloxane constituting a capsule wall. The present invention was thus completed.
The term xe2x80x9ccontinuous phasexe2x80x9d and xe2x80x9cdispersed phasexe2x80x9d usually represent a dispersing medium and a dispersed phase before formation of a wall of a microcapsule respectively. In this specification, an outer phase and an inner phase after formation of a wall of a microcapsule are also called and referred to as xe2x80x9ccontinuous phasexe2x80x9d and xe2x80x9cdispersed phasexe2x80x9d, respectively.
According to the present invention, organopolysiloxane constituting a wall of a microcapsule can be synthesized directly from the compound (B) belonging to the so-called hydroxysilanes. Further, the above-described organopolysiloxane can constitute a capsule wall necessary for producing a microcapsule containing core material, thus not requiring formation of a capsule wall by a conventional coacervation method.
The present invention provides a microcapsule containing core material and a capsule wall, in which the capsule wall of the microcapsule comprises:
organopolysiloxane synthesized by polycondensing a compound (B), monomer or monomeric mixture, wherein compound (B) contains one or more compounds represented by the general formula (II):
RnSi(OH)mY(4xe2x88x92mxe2x88x92n)xe2x80x83xe2x80x83(II)
wherein, m represents an integer from 1 to 4; n represents an integer from 0 to 3; m+nxe2x89xa64; R represents an organic group in which a carbon atom is directly connected to a silicone atom, and when n is greater than 1, each of the R groups may be the same or different; and Y represents at least one group selected from the group consisting of an alkoxy group, hydrogen and siloxy group, and when (4xe2x88x92mxe2x88x92n) is greater than 1, each of the groups Y may be the same or different; provided that the compound (B) comprises at least one compound of formula(II) wherein m=2 or 3 and at least one of R group possesses affinity for at least one of a continuous phase and a dispersed phase.
The present invention further provides a method for producing a microcapsule containing core material which comprises a process wherein the compound (B) is polycondensed to synthesize organopolysiloxane and form the capsule wall.
The compound (B), which is used for producing a microcapsule having a core material encapsulated therein, as provided by the present invention, is usually obtained by hydrolyzing a compound (A), monomer or monomeric mixture, wherein compound (A) contains one or more compounds represented by the following general formula (I):
RnSiX(4xe2x88x92n)xe2x80x83xe2x80x83(I)
wherein, n represents an integer from 0 to 3; R represents an organic group in which a carbon atom is directly connected to a silicone atom, and when n is greater than 1, each of the R groups may be the same or different; and X represents at least one group selected from the group consisting of a hydroxyl group, hydrogen, alkoxy group, halogen group, carboxyl group, amino group and siloxy group, and when (4xe2x88x92n) is greater than 1, each of the groups X may be the same or different; provided that the compound (A) contains at least one compound of formula (I) having an R group which possesses affinity for at least one of a continuous phase and a dispersed phase.
In the present invention, the term xe2x80x9cmicrocapsulexe2x80x9d means a capsule such as a microcapsule, nanocapsule and the like, and thus has a broad meaning in comparison with the typical narrower meaning of the term xe2x80x9cmicrocapsulexe2x80x9d. For example, in general, a xe2x80x9cmicrocapsulexe2x80x9d in a narrow sense means a capsule having a particle size of 1 xcexcm to 1 mm and a xe2x80x9cnanocapsulexe2x80x9d means a capsule having a particle size less than 1 xcexcm. As such, unless otherwise mentioned herein, the term xe2x80x9cmicrocapsulexe2x80x9d means a microcapsule in its broad sense in this specification and includes both microcapsules and nanocapsules. The phrase xe2x80x9cmicrocapsule containing core materialxe2x80x9d means a microcapsule containing core material in the hollow space formed by a capsule wall.
The compound (B) is a compound or a group of two or more compounds selected from those represented by the general formula (II). At least one compound constituting the compound (B) is represented by the general formula (II) wherein m=2 or 3. At least one compound constituting the compound (B) is a compound having at least one R group which possess affinity for at least one of a continuous phase and a dispersed phase.
The capsule wall of the microcapsule containing core material of the present invention is formed by polycondensing the compound (B) to synthesize organopolysiloxane.
The condensation of the compound (B) is a reaction in which a xe2x80x94SiOH group in the general formula (II) is reacted with xe2x80x94SiLxe2x80x94 (wherein, L represents a leaving group such as a hydroxyl group and the like) in aother molecule constituting the compound (B) or another prepolymer to form an xe2x80x94SiOSixe2x80x94 linkage. By this condensation reaction, organopolysiloxane is formed which constitutes a capsule wall.
As explained below, in the production of a microcapsule containing core material of the present invention, the condensation of the compound (B) is conducted to a certain extent to prepare a prepolymer of the compound (B) before the formation of organopolysiloxane, which constitutes a capsule wall. Therefore, the prepolymer is also constituted by organopolysiloxane formed by the condensation reaction.
The formulation of the organopolysiloxane which is formed as described above and constitutes the capsule wall in the present invention or a prepolymer is represented by the following general formula:
(R3SiO1/2)h(R2SiO)i(RSiO3/2)j(SiO2)k(Rxe2x80x2O1/2 )pxe2x80x83xe2x80x83(III)
wherein, R represents an organic group in which a carbon atom is directly connected with a silicon atom, or represents hydrogen and when two or more R groups are present, they may be the same or different; h, i, j, k represents 0 or a positive integer; Rxe2x80x2 represents an alkyl group or hydrogen; p represents 0 or a positive integer; and 0xe2x89xa6h+pxe2x89xa6j+2k+2.
As described above, if two or more R groups are connected to one silicon atom in the general formula (III), the R groups may be the same or different each other. The formulations shown in parentheses directly before subscripts h, i, j may all be the same or different. For example, the R groups in (R3SiO1/2)h may all be the same or different.
Organopolysiloxane constituting a prepolymer grows to be a larger polymer constituting a capsule wall, by way of condensation reaction of SiOH on a prepolymer with SiL (wherein, L represents a leaving group such as a hydroxyl group and the like) on another prepolymer. Therefore, although both organopolysiloxane constituting a capsule wall and organopolysiloxane constituting a prepolymer are represented by the above-described general formula (III), the values of h, i, j, k and p in the general formula (III) are different in the prepolymer and the capsule wall. Namely, when the above-described general formula (III) represents organopolysiloxane constituting a capsule wall, at least one of i and j is such a positive integer that a polymer sufficient to form a microcapsule is obtained. When the above-described general formula (III) represents organopolysiloxane constituting prepolymer, h, i, j and k represent 0 or a positive integer that is smaller than the h, i, j and k when the above-described general formula (III) represents organopolysiloxane constituting a capsule wall. The value of p depends on the extent of hydrolysis of the compound (B) obtained by hydrolysis of the compound (A), and the extent of condensation reaction of the compound (B). It is in the range wherein organopolysiloxane constituting a prepolymer and a capsule wall is sufficiently formed.
In an organopolysiloxane synthesized by polycondensation of the compound (B), an alkoxy group, a hydroxyl group and the like may partially remain on a silicon atom, or none of them may remain at all.
The compound (B) used for producing the microcapsule of the present invention having a core material therein is obtained by hydrolysis of the compound (A). The compound (A) is a compound or a group of two or more compounds selected from the group of compounds represented by the general formula (I).
The method for producing the microcapsule containing core materials of the present invention include processes using the following steps in order:
xe2x80x9c(1) Producing the compound (B) by hydrolysis of the compound (A)xe2x80x9d,
xe2x80x9c(2) Polycondensating by neutralizing of the compound (B)
xe2x80x9c(3) Mixing and emulsificating with a core material and/or a second liquid phasexe2x80x9d, and
xe2x80x9c(4) Curing treatmentxe2x80x9d.
Further to the above steps, an xe2x80x9cOver coat treatmentxe2x80x9d, mentioned below or a xe2x80x9cSurface treatment by the compound (A)xe2x80x9d (hereinafter, abbreviated as xe2x80x9cSurface treatmentxe2x80x9d) may also be carried out before the xe2x80x9cCuring treatmentxe2x80x9d step, if necessary or desired.
Examples of the compound (A) used in the production method of the present invention include a compound or a group of compounds carrying a hydrophilic group, a compound or a group of compounds carrying a hydrophobic group, a compound or a group of compounds carrying a group having affinity with a fluorocarbon, tetraalkoxysilane, a compound or a group of compounds carrying an amphiphatic group, a compound or a group of compounds carrying a surface active group, and the like. The term xe2x80x9camphiphaticxe2x80x9d as used herein referrs to means having affinity against both of two media, which can not mix with each other, and the amphiphatic group is a group carrying both groups having mutually different affinities such as a hydrophilic group and a hydrophobic group.
The compound (A) used in the production method of the present invention may be composed of one kind of compound and/or one kind of group of compounds or be composed of a combination of several kinds of compounds and/or several kinds of groups of compounds. For example, the compound (A) may be composed of a compound carrying a hydrophilic group and a compound carrying a hydrophobic group.
The kind of the compound (A), and the proportion of several kinds of compounds and/or several kinds of groups of compounds, when the compound (A) is composed of several kinds of compounds and/or several kinds of groups of compounds, is preferably selected so that a prepolymer formed by condensation of the compound (B) obtained by hydrolysis of the compound (A) possess affinity with at least one of a continuous phase and dispersed phase, and the prepolymer formed is dispersed steadily.
In a compound carrying a hydrophilic group which composes compound (A), it is preferable that the R group in the general formula (I) carries a hydrophilic group, and the R group carrying a hydrophilic group is connected to a silicon atom. Two or more R groups carrying a hydrophilic group maybe connected to one silicon atom. When a plurality of hydrophilic groups are connected to one R group, the plurality of hydrophilic groups may include two or more kinds of hydrophilic groups. In addition to a hydrophilic group, a hydrophobic group and a group having affinity with a fluorocarbon may be connected to R group carrying a hydrophilic group.
Examples of a compound which derives a hydrophilic group in the compound (A) include polyethers such as a polyoxyethylene, polyoxypropylene and polyoxyethylene-polyoxypropylene copolymer, saccharides including polysaccharides and monosaccharides such as pullulan, sorbitol, chitin and chitosan or amino sugars, proteins, antibodies, hydrolyzed protein, polyamino acids, carboxylic acids or salts and derivatives thereof, polycarboxylic acids or salts and derivatives thereof, sulfuric acid or salts and derivatives thereof, phosphoric acid or salts and derivatives thereof, sulfonic acid or salts and derivatives thereof, phosphonic acid or salts and derivatives thereof, quaternary ammonium groups, amine or salts thereof, polyamines or salt thereof, and the like. The compound which derives a hydrophilic group in the compound (A) is not limited to the above-exemplified compounds. As a group which is connected with the above-exemplified hydrophilic group to form hydrophilic group xe2x80x9cRxe2x80x9d, xe2x80x94CH2xe2x80x94, xe2x80x94(CH2)2xe2x80x94, xe2x80x94(CH2)3xe2x80x94, xe2x80x94(CH2)3OCH2CH(OH)CH2xe2x80x94, xe2x80x94(CH2)3NHCOxe2x80x94, xe2x80x94(CH2)3CH(CH2COOH)COxe2x80x94, xe2x80x94(CH2)3CH(COOH)CH2COxe2x80x94 and the like are exemplified, and a silicon atom is connected to the left side of this partial structural formula and the above-described hydrophilic group is connected to the right side of the formula.
Specific examples of a compound carrying a hydrophilic group and composing the compound (A) include polyoxyethylene-modified silicones [for example, KF-354 (trade name)] carrying, as a hydrophilic group, a polyether such as a polyoxyethylene, polyoxypropylene and polyoxyethylene-polyoxypropylene copolymer, polyethoxypropyltrimethoxysilanes [for example, KBM-641 (trade name) manufactured by Shin-Etsu Chemical Co., Ltd.], N-[2-hydroxy-3-(3xe2x80x2-trihydroxysilyl)propoxy]propyl hydrolyzed protein derived from xcex3-glycidoxypropyltriethoxysilane and hydroxylzed protein, N-[2-hydroxy-3-(3xe2x80x2-dihydroxymethylsilyl)propoxy]propyl hydrolyzed protein derived from xcex3-glycidoxypropylmethyldiethoxysilane and hydroxylzed protein(JP-A-8-67608), and compounds derived from the hydrophilic substance carrying a hydrophilic group as described above and a silane coupling agent such as xcex2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, xcex3-[N-(xcex2-aminoethyl)amino]propylmethyldimethoxysilane, xcex3-[N-(xcex2-aminoethyl)amino]propyltrimethoxysilane, xcex3-[N-(xcex2-aminoethyl)amino]propyltriethoxysilane, xcex3-aminopropyltrimethoxysilane, xcex3-aminopropyltriethoxysilane, xcex3-(N-phenylamino)propyltrimethoxysilane, xcex3-chloropropyltrimethoxysilane, xcex3-mercaptopropyltrimethoxysilane, xcex3-isocyanate propyltriethoxysilane, 3-triethoxysilylpropylsuccinic anhydride and the like. The compound carrying a hydrophilic group and composing compound (A) is not limited to the above-described examples.
Regarding the above-described polyethers such as a polyoxyethylene, polyoxypropylene and polyoxyethylene-polyoxypropylene copolymer, it is preferable that the number-average polymerization degree of oxyethylene and oxypropylene is from 1 to 2000, particularly from 4 to 800.
Preferable examples of the hydrolyzed protein in the above-described N-[2-hydroxy-3-(3xe2x80x2-trihydroxysilyl)propoxy]propyl hydrolyzed protein and N-[2-hydroxy-3-(3xe2x80x2-dihydroxymethylsilyl)propoxy]propyl hydrolyzed protein include, but are not limited to, hydrolysates of animal-derived protein such as collagen, elastin, keratin, fibroin (silk), sericin (silk), casein and conchiolin, vegetable-derived protein such as wheat protein, soybean protein, sesame protein and zein (corn protein), and microorganism-derived protein such as yeast protein. It is preferable that the number-average molecular weight of the hydrolyzed protein is from about 100 to 50000, particularly from about 200 to 5000.
In a compound carrying a hydrophobic group which composes the compound (A), it is preferable that the R group in the general formula (I) carries a hydrophobic group and the R group carrying a hydrophobic group is connected to a silicon atom. Two or more R groups carrying a hydrophobic group may be connected to one silicon atom, and a plurality of hydrophobic groups are connected to one R group. The plurality of hydrophilic groups may include two or more kinds of hydrophobic groups. In addition to a hydrophobic group, a group having affinity with a fluorocarbon may be connected to an R group carrying a hydrophobic group.
Examples of the hydrophobic group include a straight-chain hydrocarbon, branched hydrocarbon, unsaturated hydrocarbon, aromatic compounds, esters and the like. It is preferable that one or more of these functional groups are connected to R, although the hydrophobic group is not limited to the above-exemplified compounds.
Specific examples of a compound carrying a hydrophobic group and composing the compound (A) include methyldiethoxysilane, methyldichlorosilane, methyltrimethoxysilane, methyltriethoxysilane, methyltrichlorosilane, dimethyldimethoxysilane, dimethyldiethoxysilane, dimethyldichlorosilane, phenyltrimethoxysilane, phenyltriethoxysilane, phenyltrichlorosilane, diphenyldimethoxysilane, diphenyldiethoxysilane, diphenyldichlorosilane, hexyltrimethoxysilane, octyltriethoxysilane, decyltrimethoxysilane, stearoxypropyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris-(xcex2-methoxyethoxy)silane, vinyltrichlorosilane, xcex3-methacryloxypropylmethyldimethoxysilane, xcex3-methacryloxypropyltrimethoxysilane, xcex3-methacryloxypropylmethyldiethoxysilane, xcex3-methacryloxypropyltriethoxysilane, xcex3-chloropropyltrimethoxysilane, xcex3-mercaptopropyltrimethoxysilane, octadecyldimethyl-(3-trimethoxysilylproyl)ammonium chloride, dimethylhexadecyl-(3-trimethoxysilylpropyl)ammonium chloride and the like. The specific examples further include compounds derived from the hydrophobic substance carrying a hydrophobic group as described above and a silane coupling agent such as vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(xcex2-methoxyethoxy)silane, vinyltrichlorosilane, xcex3-methacryloxypropylmethyldimethoxysilane, xcex3-methacryloxypropyltrimethoxysilane, xcex3-methacryloxypropylmethyldiethoxysilane, xcex3-methacryloxypropyltriethoxysilane, xcex3-glycidoxypropyltriethoxysilane, xcex3-glycidoxypropylmethyldiethoxysilane, xcex2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, xcex3-[N-(xcex2-aminoethyl)amino]propylmethyldimethoxysilane, xcex3-[N-(xcex2-aminoethyl)amino]propyltrimethoxysilane, xcex3-[N-(xcex2-aminoethyl)amino]propyltriethoxysilane, xcex3-aminopropyltrimethoxysilane, xcex3-aminopropyltriethoxysilane, xcex3-(N-phenylamino)propyltrimethoxysilane, xcex3-chloropropyltrimethoxysilane, xcex3-mercaptopropyltrimethoxysilane, xcex3-isocyanatepropyltriethoxysilane and 3-triethoxysilylpropylsuccinic anhydride. Further, as specific examples of the compound represented by the general formula (I) in which X is a siloxy group, octamethylcyclotetrasiloxane, dihydrogenehexamethylcyclotetrasiloxane and trihydrogenepentamethylcyclotetrasiloxane are listed. The compound carrying a hydrophobic group and composed of the compounds (A) is not limited to the above exemplified compounds.
In the compound carrying a group having affinity with a fluorocarbon, it is preferable that the R group in the general formula (I) carries a group having affinity with a fluorocarbon, and the R group carrying a group having affinity with a fluorocarbon is connected to one silicon atom. Two or more R groups carrying a group having affinity with a fluorocarbon may be connected to one silicon atom, and a plurality of groups having affinity with a fluorocarbon may be connected to the R group. The plurality of groups having affinity with a fluorocarbon may include two or more kinds of groups having affinity with a fluorocarbon.
Examples of the compound carrying a group having affinity with a fluorocarbon and composing the compounds (A) include C8F17CH2CH2Si(OCH3)3, CF3CH2CH2Si(OCH3)3, and compounds derived from a substance having affinity with a fluorocarbon and a silane coupling agent such as vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(xcex2-methoxyethoxy)silane, vinyltrichlorosilane, xcex3-methacryloxypropylmethyldimethoxysilane, xcex3-methacryloxypropyltrimethoxysilane, xcex3-methacryloxypropylmethyldiethoxysilane, xcex3-methacryloxypropyltriethoxysilane, xcex3-glycidoxypropyltriethcxysilane, xcex3-glycidoxypropylmethyldiethoxysilane, xcex2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, xcex3-[N-(xcex2-aminoethyl)amino]propylmethyldimethoxysilane, xcex3-[N-(xcex2-aminoethyl)amino]propyltrimethoxysilane, xcex3-[N-(xcex2-aminoethyl)amino]propyltriethoxysilane, xcex3-aminopropyltrimethoxysilane, xcex3-aminopropyltriethoxysilane, xcex3-(N-phenylamino)propyltrimethoxysilane, xcex3-chloropropyltrimethoxysilane, xcex3-mercaptopropyltrimethoxysilane, xcex3-isocyanatepropyltriethoxysilane and 3-triethoxysilylpropylsuccinic anhydride. The compound carrying a group having affinity with a fluorocarbon and composing the compound (A) is not is not limited to the above exemplified compounds.
As specific examples of the compound having both a hydrophilic group and a hydrophobic group, which composes the compound (A), a compound which generates N-[2-hydroxy-3-(3xe2x80x2-dihydroxymethylsilyl)propoxy]propyl hydrolyzed protein by hydrolyzing the substituents such as an alkoxy group and the like are exemplified.
When the microcapsule containing core material, made from the compound (A), is dispersed in water or hydrophilic continuous phase, the compound (A) is as follows.
When a hydrophilic group in the compound (A) is a polyether such as a polyoxyethylene, polyoxypropylene and polyoxyethylene-polyoxypropylene copolymer, it is preferable that total number-average polymerization degree of oxyethylene and oxypropylene is from 10 to 1000, particularly from about 20 to 400. When the compound (A) is a hydrolyzed protein, it is preferable that the number-average molecular weight thereof is from 200 to 50000, particularly from about 400 to 5000.
It is preferable that the molar ratio of a compound (A) carrying a hydrophilic group (including the case wherein the R group carries a hydrophilic group and a hydrophobic group together) to a compound (A) carrying a hydrophobic group is from about 1:0 to 1:1000, particularly from about 1:2 to 1:200, in terms of monomers.
When a monomethyl type compound, wherein only one R group in the formula (I) is a methyl group, is used as the compound (A) carrying a hydrophobic group, it is preferable that at least one compound selected from the group consisting of methyltriethoxysilane, methyltrimethoxysilane and methyltrichlorosilane is used, or that such a compound is used in combination with at least one compound selected from the group consisting of dimethyldiethoxysilane, dimethyldimethoxysilane, dimethyldichlorosilane, octamethylcyclotetrasiloxane, phenyltriethoxysilane, hexyltrimethoxysilane, octyltriethoxysilane, decyltrimethoxysilane and stearoxypropyltrimethoxysilane. The molar ratio of the monomethyl type compound to another compound carrying a hydrophobic group may be from 100:0 to 0:100, but it is preferable that the molar ratio is from about 100:3 to 100:80, in terms of monomers. The monomethyl type compound and the other compounds carrying a hydrophobic group are not limited to the above-exemplified compounds.
When the microcapsule containing core material is made from the compound (A), and is dispersed in a hydrophobic continuous phase or non-aqueous continuous phase, the compound (A) is as follows.
When a hydrophilic group in the compound (A) is a polyether such as a polyoxyethylene, polyoxypropylene and polyoxyethylene-polyoxypropylene copolymer, it is preferable that total number-average polymerization degree of oxyethylene and oxypropylene is from 3 to 20, particularly from 5 to 10. When the compound (A) is a hydrolyzed protein, it is preferable that the number-average molecular weight thereof is from about 100 to 2000, particularly from about 200 to 1000.
When a monomethyl type compound wherein only one R group in the formula (I) is a methyl group is used as the compound (A) carrying a hydrophobic group, it is preferable that at least one compound selected from the group consisting of methyltriethoxysilane, methyltrimethoxysilane and methyltrichlorosilane is used, or such a compound is used in combination with at least one compound selected from the group consisting of dimethyldiethoxysilane, dimethyldimethoxysilane, dimethyldichlorosilane, octamethylcyclotetrasiloxane, phenyltriethoxysilane, hexyltrimethoxysilane, octyltriethoxysilane, decyltrimethoxysilane and stearoxypropyltrimethoxysilane. The molar ratio of the monomethyl type compound to another compound carrying a hydrophobic group may be from 100:0 to 0:100, but it is preferable that the molar ratio is from about 10:100 to 80:100, in terms of monomers. The monomethyl type compound and the other compounds carrying a hydrophobic group are not limited to the above-exemplified compounds.
Hydrolysis of the compound (A) will be described below.
The compound (B) is usually obtained by hydrolysis of the compound (A). As a medium for this hydrolysis, water is usually used. In addition, a small amount of an organic solvent soluble in water, salts, protein modifying agent such as urea, and the like may also be added to water. Addition of these additives is effective when neutralization after hydrolysis of the compound (A) or emulsification by mixing with a second liquid phase are conducted at a temperature of not more than 0xc2x0 C., and is one preferable method. Further, in a process from hydrolysis of the compound (A) to production of a prepolymer via the compound (B), it is preferable to use a medium having a viscosity of 10 to 2000 mPaxc2x7s before addition of the compound (A), to control reaction speed so that the condensation reaction rate does not rise so much, to prevent deposition following insolubilization of the prepolymer, and to stabilize the solution. As a thickening substance for preparing a medium having a viscosity of 10 to 2000 mPaxc2x7s, polyvinyl alcohol, polyacrylamide, carboxymethylcellulose sodium, carboxymethyldextran, hydroxyethylcellulose, carageenan, chitin, chitosan, polypeptide, gelatin, sericin and the like are exemplified. In particular, an aqueous gelatin solution having a viscosity of 10 to 2000 mPaxc2x7s is exemplified.
It is preferable that the hydrolysis of the compound (A) is conducted at a temperature from xe2x88x925xc2x0 C. to 90xc2x0 C., particularly from 5xc2x0 C. to 75xc2x0 C., with complete stirring (i.e. under stirring conditions).
The hydrolysis of the compound (A) may be conducted at either an acidic pH or a basic pH. Selection of these properties depends on the nature of the compound (A).
When the hydrolysis of the compound (A) is conducted at an acidic pH, it is preferably conducted at pH 1-5, particularly of 2-4. When acidity in hydrolysis is too strong, a core material may not be later incorporated thereto sufficiently, and a hyaline substance may be partially produced, though it depends also on the constitution and concentration of the compound (A). Examples of the acid to be used include an organic acid such as acetic acid and the like, and an inorganic acid such as hydrochloric acid, sulfuric acid, phosphoric acid and the like. Particularly, when the compound (A) carries a hydrophilic group which is a hydrolyzate of an animal-derived protein such as collagen, elastin, keratin, fibroin (silk), sericin (silk), casein and conchiolin, if the hydrolysis of the compound (A) is conducted at an acidic pH, preferable results are obtained for obtaining a microcapsule containing core material.
When the hydrolysis is conducted at a basic pH, it is preferably conducted at a pH of 7.5 to 11.5, particularly of 8 to 10. When basicity in hydrolysis is too strong, a core material may not be later incorporated therein sufficiently, and a hyaline substance may be partially produced, though it depends also on the constitution and concentration of the compound (A). As the alkali to be used, for example, sodium hydroxide, potassium hydroxide and the like are listed. Particularly, when the compound (A) carries a hydrophilic group which is a hydrolyzate of vegetable-derived protein such as for example wheat protein, soybean protein and sesame protein, if the hydrolysis of the compound (A) is conducted at a basic pH, preferable results are obtained for obtaining a microcapsule containing core material.
The compound (B) produced by hydrolysis of the compound (A) is polycondensed usually by neutralization.
The neutralization is preferably conducted at a temperature from xe2x88x9230xc2x0 C. to 80xc2x0 C., particularly from xe2x88x925xc2x0 C. to 55xc2x0 C. with sufficient stirring. As acids and akalis used for the neutralization, the same compounds as those listed for the above-described hydrolysis are exemplified. As the medium for the neutralization, water is exemplified.
In the production method of the present invention, production of the compound (B) and polycondensation by neutralization are conducted to a certain extent before mixing and emulsification with a core material and/or second liquid phase, in order to prepare a prepolymer of the compound (B) previously. When at least one compound (B) which carries at least one hydrophilic R, particularly, carries at least one polypeptide having a number-average molecular weight of about 100 to 50000, as R, or a polyoxyethylene having a number-average polymerization degree of 1 to 2000, as R, is used, this method is particularly preferable since the prepolymer can be stabilized in this method.
Extent of the polycondensation of the compound (B) by neutralization to be conducted before mixing and emulsification with a core material and/or second liquid phase may be changed according to the other conditions as long as the formed prepolymer is stable. In other words, mixing and emulsification with a core material and/or second liquid phase must be conducted before the formed prepolymer become unstable.
When the prepolymer is unstable and easily precipitated, a method for preparing a prepolymer by hydrolysis of the compound (A) in a viscous solution such as an aqueous gelatin solution and the like is preferable since the prepolymer can be stabilized in this method.
It is preferable that after preparation of the prepolymer, this prepolymer in an aqueous solvent is mixed with a hydrophobic substance and/or a non-aqueous solvent to prepare an emulsion.
In the above-described method, after mixing of a hydrophobic substance and/or a non-aqueous solvent, the prepolymer causes mutual condensation and grows to a larger polymer to become organopolysiloxane constituting a capsule wall.
Then, mixing and emulsification with a core material and/or second liquid phase is utilized as described below.
The following methods are exemplified methods for mixing and emulsification with a core material and/or second liquid phase:
In the case of a microcapsule containing core material dispersed in water or a hydrophilic dispersing medium, a method in which a prepolymer is prepared in an aqueous dispersing medium, then, a core material in the form of liquid (second liquid phase) alone, or a core material and a solvent thereof (second liquid phase), is added.
In the case of a microcapsule containing core material dispersed in a hydrophobic dispersing medium or a non-aqueous dispersing medium, when the core material is soluble in an aqueous solvent or is hydrophilic, a method in which, to an aqueous solvent dispersion of a prepolymer, the core material is added as it is, or after being dissolved in an aqueous solvent, and the resulted liquid is mixed with a solvent immiscible with the aqueous solvent (continuous phase in the second liquid phase) to invert the phase and emulsify. The core material may be added after the inversion of the phase and emulsification thereof.
In the method of the present invention, since a core material can be incorporated at neutral condition, a microcapsule containing a substance unstable at conditions other than neutral can be produced. Mixing and emulsification with a core material and/or second phase are usually conducted at from xe2x88x9230xc2x0 C. to 95xc2x0 C., particularly from xe2x88x925xc2x0 C. to 60xc2x0 C. Examples of the core material utilized are provided below.
Examples of the core material utilized include water, fatty acids particularly higher fatty acid, hydrocarbons, organic solvents, esters, phenols, silicones, silanes, metal alkoxides, alcohols particularly higher alcohol, animal and vegetable oils, extracted components, electrodonative coloration organic compounds, coloring matters, ultraviolet ray absorbers, vitamins, effective drug components, aroma components, preservative, sterilizer, salts; amino acid and its derivatives, protein, hydrolyzed protein and its derivatives, saccharides, polysaccharide, enzymes, fluorocarbon-like substances, and the like. The core material is not limited to the above-exemplified substances.
Examples of the higher fatty acids include capric acid, lauric acid, miristic acid, palmitic acid, stearic acid, behenic acid, 12-hydroxystearic acid, undecylenic acid, lanolin fatty acid, isostearic acid, linoleic acid, oleic acid, linolenic acid, arachidonic acid, eicosapentaenic acid, docosahexaenic acid and the like.
Examples of the hydrocarbons include liquid paraffin, isoparaffin, ozokerite, pristan, ceresin, vaseline, microcrystalline wax and the like.
Examples of the organic solvent include hexane, heptane, octane, benzene, toluene, xylene, chlorobenzene, ethyl acetate, butyl acetate and the like.
Examples of the esters include isopropyl miristate, cetyl octanoate, octyldodecyl miristate, isopropyl palmitate, butyl stearate, hexyl laurate, miristyl miristate, decyl oleate, hexyldecyl dimethyloctanoate, cetyl lactate, miristyl lactate, lanolin lactate, methyl isostearate, isocetyl stearate, cholesteryl 12-hydroxystearate, ethylene glycol di-2-ethylhexylate, dipentaerythrithol fatty ester, n-alkyl glycol monoisostearate, propylene glycol dicaprate, neopentyl glycol dicaprate, glyceryl tricaprate, isostearyl neopentanoate, diisosteary malate, glyceryl monostearate, glyceryl distearate, glyceryl di-2-heptylundecanoate, trimethylolpropane tri-2-ethylhexanoate, trimethylolpropane triisostearate, neopentyl glycol di-2-ethylhexanoate, pentaerythritol tetra-2-ethylhexanoate, glyceryl tri-2-ethylhexanoate, cetyl 2-ethylhexanoate, 2-ethylhexyl isononanoate, isononyl isononanoate, isodecyl isononanoate, isotridecyl isononanoate, 2-ethylhexyl palmitate, glyceryl trimiristate, glyceryl trioctanoate, glyceryl triisopalmitate, castor oil fatty acid methyl ester, oleyl oleate, glyceryl acetate, 2-heptylundecyl palmitate, diisopropyl adipate, diisobutyl adipate, N-lauroyl-L-glutamic acid-2-octyldodecyl ester, 2-heptylundecyl adipate, ethyl laurate, di-2-ethylhexyl sebacate, 2-hexyldecyl miristate, 2-hexyldecyl palmitate, 2-hexyldecyl adipate, 2-hexyldecyl succinate, diisopropyl sebacate and the like.
Examples of the phenols include t-butylphenol, nonylphenol, dodecylphenol, xcex1-naphthol, xcex2-naphthol, hydroquinone monomethyl ether, p-chlorophenol, p-bromophenol, o-phenylphenol, p-phenylphenol, methyl p-hydroxybenzoate, ethyl p-hydroxybenzoate, propyl p-hydroxybenzoate, 3-isopropylcatechol, p-t-butylcatechol, 4,4xe2x80x2-methylenediphenol, bisphenol A, 1,2-dihydroxynaphthalene, chlorocatechol, bromocatechol, 2,4-dihydroxybenzophenone, phenolphthalein, methyl gallate, ethyl gallate, propyl gallate, hexyl gallate, octyl gallate, dodecyl gallate, cetyl gallate, stearyl gallate, tannic acid, phenol resin, zinc salicylate, zinc t-butylsalicylate and the like.
Examples of the silicones include dimethylpolysiloxane, methylphenylpolysiloxane, dimethylsiloxane-methylstearoxysiloxane copolymer, dimethylsiloxane-methylmethoxysiloxane copolymer, dimethylsiloxane-methylethoxysiloxane copolymer, trimethylsiloxysilicic acid, methylcyclopolysioxane, methylhydrogenpolysiloxane, high polymer methylpolysiloxane, crosslinked-type methylpolysiloxane and the like.
Examples of the silanes include methyltrimethoxysilane, methyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, hexyltrimethoxysilane, octyltrimethoxysilane, decyltrimethoxysilane, tetramethoxysilane, tetraethoxysilane and the like.
Examples of the metal alkoxides include trimethyl borate, triethyl borate, tetraethyl titanate, tetraisopropyl titanate and the like.
Examples of the higher alcohols include capryl alcohol, lauryl alcohol, miristyl alcohol, cetyl alcohol, stearyl alcohol, arachyl alcohol, behenyl alcohol, oleyl alcohol, ketostearyl alcohol, monostearyl glyceryl ether, 2-decyltetradecanol, 2-hexyldecanol, 2-hexyldodecanol, 2-octyldodecanol, 2-heptylundecanol, lanolin alcohol, cholesterol, phytosterol, isostearyl alcohol and the like.
Examples of the animal and vegetable oils include avocado oil, tsubaki oil, macadamia nut oil, corn oil, olive oil, evening primrose oil, rapeseed oil, yolk oil, sesame oil, persic oil, wheat germ oil, camellia sasanqua oil, castor oil, curing castor oil, linseed oil, safflower oil, cotton seed oil, curing cotton seed oil, soybean oil, curing soybean oil, peanut oil, tee nip oil, Japanese Nutmeg oil, rice bran oil, chinese tung oil, japanese tung oil, cinnamon oil, jojoba oil, germ oil, almond oil, cocoa oil, palm oil, curing palm oil, horse tallow, turtle oil, mink oil, squalane, squalene, orange roughy oil, beef tallow, curing beef oil, beef bone oil, neat""s foot oil, mutton oil, lard, train oil, curing train oil, fish oil, curing fish oil, lanolin, lanolin alcohol, hydrogenater lanolin, lanolin acetate, liquid lanolin, lanolin fatty acid isopropyl ester, cholesteryl lanonate, cyclic lanolin, polyoxyethylenelanolin alcohol ether, polyoxyethylenelanolin alcohol acetate, polyethylene glycol lanolin fatty acid, polyoxyethylene hydrogenater lanolin alcohol ether, carnauba wax, candelilla wax, jojoba wax, hard lanolin, Japan wax, indian millet wax, cotton wax, wax myrtle, insect wax, montan wax, rice bean wax, shellac wax, jojoba wax, bee wax, train wax, jojoba alcohol, abietic acid, hydrogenated abietic acid and the like.
Examples of the electrodonative coloration organic compound include diarylphthalides, polyaryl carbinols, leuco auramines, acyl auramines, aryl auramines, rhodamine-xcex2-lactams, indolines, spiropyrans, fluorans and the like. Specific examples thereof include crystal violet lactone, malachite green lactone, Michler""s hydrol, cryltal violet carbinol, malachite green carbinol, N-(2,3-dichlorophenyl)leuco auramine, N-benzoyl auramine, N-acetyl auramine, N-phenyl auramine, rhodamine-xcex2-lactam, 2-(phenyliminoethanedilidene)-3,3-dimethylindoline, N-3,3-trimethylindolinobenzspirolane, 3-dietylamino-6-methyl-7-chlorofluoran, 3-diethylamino-7-methoxyfluoran, 3-diethylamino-6-benzyloxyfluoran, 1,2-benz-6-diethylaminofluoran and the like.
Examples of the coloring matters include colorless white pigments such as titanium dioxide, zinc oxide and the like, inorganic red pigments such as iron oxide (red iron oxide), iron titanate and the like, inorganic brown pigments such as xcex3-iron oxide and the like, inorganic yellow pigments such as yellow iron oxide, loess and the like, inorganic black pigments such as black iron oxide, carbon black, lower titanium oxide and the like, inorganic violet pigments such as mango violet, cobalt violet and the like, inorganic green pigments such as chromium oxide, chromium hydroxide, cobalt titanate and the like, inorganic blue pigments such as ultramarine, iron blue and the like, organic dyes such as Red 201, Red 202, Red 204, Red 205, Red 218, Red 220, Red 225, Red 226, Red 228, Red 405, Orange 201, Orange 203, Orange 204, Yellow 401, Green 202, Blue 404 and the like, organic pigments of zirconium, barium or aluminum lake and the like such as Red 3, Red 104, Red 106, Red 227, Red 230, Red 401, Red 505, Orange 205, Yellow 4, Yellow 5, Yellow 202, Yellow 203, Green 3, Violet 201, Blue 11 and the like, natural pigments such as chlorophyll, xcex2-carotene and the like, mica titanium, red iron oxide-treated mica titanium, yellow iron oxide-treated mica titanium, black iron oxide-treated mica titanium, iron oxide- yellow iron oxide-treated mica titanium, ultramarine-treated mica titanium, carmine-treated mica titanium, chromium oxide-treated mica titanium, carbon black-treated mica titanium and the like. Further, examples thereof include talc, kaolin, mica, phlogopite, sericite, white mica, synthetic mica, epidolite, lithia mica, vermiculite, inorganic powders such as apatite fluoride, hydroxyapatite, ceramic powder, metal soap (zinc miristate, calcium palmitate, aluminum stearate and the like), boron nitride, silica-alumina, silica-magnesia, bentonite, fuller""s earth, Japanese acid clay, active white earth, montmorillonite, attapulgite and the like; and organic powder such as a polyamide resin powder (nylon powder), polyethylene powder, polymethyl methacrylate powder, polystyrene powder, styrene-acrylic acid copolymer resin powder, benzoguanamine resin powder, polyethylene tetrafluoride powder, cellulose powder; and the like.
Examples of the ultraviolet ray absorbers include salicylic acid-based ultraviolet ray absorbers such as phenyl salicylate, p-t-butylphenyl salicylate, p-octylphenyl salicylate and the like, benzophenone-based ultraviolet ray absorbers or derivatives thereof such as 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octyloxybenzophenone, 2-hydroxy-4-dodecyloxybenzophenone, 2,2xe2x80x2-dihydroxy-4,4xe2x80x2-dimethoxybenzophenone, 2,2xe2x80x2-dihydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone and the like, 2-(2xe2x80x2-hydroxy-5xe2x80x2-methylphenyl)benzotriazole, 2-(2xe2x80x2-hydroxy-5xe2x80x2-t-butylphenyl)benzotriazole, 2-(2xe2x80x2-hydroxy-3xe2x80x2,5xe2x80x2-di-t-butylphenyl)benzotriazole, 2-(2xe2x80x2-hydroxy-3xe2x80x2-t-butyl-5xe2x80x2-methylphenyl)-5-chlorobenzotriazole, 2-(2xe2x80x2-hydroxy-3xe2x80x2,5xe2x80x2-di-t-butylphenyl)-5-chlorobenzotriazole, 2-(2xe2x80x2-hydroxy-3xe2x80x2,5xe2x80x2-di-t-amylphenyl)benzotriazole, 2-[2xe2x80x2-hydroxy-3xe2x80x2-(3xe2x80x3,4xe2x80x3,5xe2x80x3,6xe2x80x3-tetrahydrophthalimidemethyl)-5xe2x80x2-methylphenyl]-benzotriazole, 2-(2xe2x80x2-hydroxyl-3xe2x80x2-dodecyl-5xe2x80x2-methylphenyl)benzotriazole, 2-(2xe2x80x2-hydroxy-3xe2x80x2-undecyl-5xe2x80x2-methylphenyl)benzotriazole, 2-(2xe2x80x2-hydroxy-3xe2x80x2-tridecyl-5xe2x80x2-methylphenyl)benzotriazole, 2-[2xe2x80x2-hydroxy-4xe2x80x2-(2xe2x80x3-ethylhexyl)oxyphenyl]benzotriazole, 2-[2xe2x80x2-hydroxy-4xe2x80x2-(2xe2x80x3-ethyloctyl)oxyphenyl]benzotriazole, 2-[2xe2x80x2-hydroxy-4xe2x80x2-(2xe2x80x3-propyloctyl)oxyphenyl]benzotriazole, 2-[2xe2x80x2-hydroxy-4xe2x80x2-(2xe2x80x3-propylheptyl)oxyphenyl]benzotriazole, 2-[2xe2x80x2-hydroxy-4xe2x80x2-(2xe2x80x3-propylhexyl)oxyphenyl]benzotriazole, 2-[2xe2x80x2-hydroxy-4xe2x80x2-(1xe2x80x3-ethylhexyl)oxyphenyl]benzotriazole, 2-[2xe2x80x2-hydroxy-4xe2x80x2-(1xe2x80x3-ethylheptyl)oxyphenyl]benzotriazole, 2-[2xe2x80x2-hydroxy-4xe2x80x2-(1xe2x80x3-ethyloctyl)oxyphenyl]benzotriazole, 2-[2xe2x80x2-hydroxy-4xe2x80x2-(1xe2x80x3-propyloctyl)oxyphenyl]benzotriazole, 2-[2xe2x80x2-hydroxy-4xe2x80x2-(1xe2x80x3-propylheptyl)oxyphenyl]benzotriazole, 2-[2xe2x80x2-hydroxy-4xe2x80x2-(1xe2x80x3-propylhexyl)oxyphenyl]benzotriazole, condensate of methyl-3-[3-t-butyl-5-(2H-benzotriazole-2-yl)-4-hydroxyphenyl]propionate with polyethylene glycol (molecular weight:about 300), derivatives or ester of p-methoxycinnamic acid such as 2-ethylhexyl p-methoxycinnamate, derivatives or ester of p-dimethylaminobenzoic acid such as 2-ethylhexyl p-dimethylaminobenzoate, derivatives or ester of cinnamic acid such as benzyl cinnamate, derivatives of anthranylate, salicylate and benzooxazole, 2,4,6-tri-(p-anilino)-1-(carboxy-2xe2x80x2-ethylhexyl)-1,3,5-triazine, derivatives of dibenzoylmethane such as 4-t-butyl-4xe2x80x2-methoxydibenzoylmethane and 4-isopropyldibenzoylmethane, franone derivatives, ferulic acid or esters thereof, xcex3-oryzanol and the like.
Examples of the vitamins include vitamins or derivatives thereof such as vitamin A, vitamin B, vitamin C, vitamin D, vitamin E, thiamine hydrochloride, pyridoxine hydrochloride, calcium panthothenate, bisbentiamine, methylmethioninesulfonium chloride and the like. Specifically, magnesium L-ascorbyl-2-phosphate, sodium L-ascorbyl-2-phosphate, tocopherol acetate and the like are exemplified.
Examples of the effective drug components include sulfur drugs such as sulfamethomidine, circulatory drugs such as calcium hobatate, papaverine hydrochloride, diltiazem hydrochloride and reserpine, breathing promoting drugs such as trimetoxynol hydrochloride, bromhexine hydrochloride and tipepidine hibenzate, antitussive expectoration drugs, antibiotics such as potassium benzylpenicillinate, sodium benzylpenicillinate, potassium phenoxymethylpenicillinate and ampicillin, carcinostatic tumor agents such as 5-fluorourasil, N-(2-tetrahydrofuryl)-5-fluorourasil and bleomycin hydrochloride, treating agent such as timepidium bromide, lidocaine hydrochloride and chlorpromazine hydrochloride, antihistamic agents such as diphenhydramine hydrochloride and chlorphenylamine maleate, antiphlogistic agent such as aspirin, quinine hydrochloride and sulpirin, bactericides such as salicylic acid, hinoki cypress, sulfur, parabenes and the like, preservatives, and in addition, photosensitive materials, cyctein or derivatives thereof, guaiazlene or derivatives thereof, glutathione or derivatives thereof, and the like.
Examples of the extracted components include oil-soluble arnica extract, aloe extract, oil-soluble dead nettle extract, matricaria extract, oil-soluble chamomile extract, oil-soluble glycyrrhiza extract, cape jasmine extract, oil-soluble mulberry extract, oil-soluble burdock extract, oil-soluble collagen extract, oil-soluble salvia extract, oil-soluble lithospermum root extract, oil-soluble linden extract, oil-soluble betula alba extract, oil-soluble field horsetail extract, oil-soluble yarrow extract, oil-soluble sage extract, Japanese green gentian extract, common thyme extract, citrus unshiu peel extract, oil-soluble juglanus regia L. extract, oil-soluble Japanese angelica root extract, oil-soluble common marigold extract, oil-soluble carrot extract, oil-soluble wild rose extract, oil-soluble loquat leaf extract, oil-soluble placental extract, oil-soluble hop extract, oil-soluble marronnier extract, oil-soluble peach leaf extract, mugwort extract, oil-soluble coix extract, lavender extract, lemon extract, orange extract, oil-soluble rosemary extract, oil-soluble royal jelly extract, green tea, Du Zhong tea or Ruibosu tea which contain tannins or flavonoids; and crude drugs of plant and animal origin or various salts thereof such as sophora japonica, scutellaria root and Souhakuhi extract.
Examples of the aroma components include oils having odor such as almond, anise, caraway, cassia, cedar leaf, cedar wood, cinnamon, citronella, clove, eucalyptus, geranium, grape fruit, lavender, lemon, lemon herb, rose oil, lime, orange flower (nerori oil), nutmeg, onion, garlic, orange, lignum vitae, orris, peppermint, pine, pine needle, rosemary, sandalwood, sassafras, spearmint, time, coffee, black tea, cherry, apple, pineapple, banana, peach, vanilla and the like.
Examples of the salts include calcium carbonate, magnesium carbonate, magnesium silicate, calcium silicate, aluminum silicate, barium silicate, barium sulfate, strontium silicate, metal tungstate, silica, zeolite, barium sulfate, calcined calcium sulfate (baked gypsum), calcium phosphate, lithium chloride, sodium chloride, potassium chloride, ammonium chloride, lithium bromide, sodium bromide, potassium bromide, lithium iodide, sodium iodide, potassium iodide, iodine, sodium sulfate, potassium sulfate, ammoniumsulfate, ammonium nitrate, lime nitrogen, lime perphosphate, baked phosphatic fertilizer, sodium phosphate and the like.
Examples of the amino acid, protein, saccharides and the like include amino acids or peptides such as potassium aspartate, magnesium aspartate, sodium glutamate, lysine hydrochloride and glutathione, animal-derived proteins such as collagen, elastin, keratin, fibroin, sericin, casein and conchiolin, vegetable-derived proteins such as wheat protein, soybean protein and sesame protein, microorganism-derived proteins such as yeast protein or hydrolysates of such proteins, placenta extract, mucopolysaccharides, urea and the like.
Examples of the enzyme include lipase, protease, super oxide, dismutase, lysozyme, alkaliphosphatase, amylase, pancreatin, glutathione peroxidase, catalase and the like.
Examples of the fluorocarbon-like substance include Fomblin HC/04 (trade name), Fomblin HC/25 (trade name) and Fomblin HC/R (trade name) which are a liquidperfluoro ether which is a kind of polyoxy perfluofoalkanes manufactured by Monteflous (Milan, Italy).
One or more of the above-described compounds can be used as core materials. However, the core material is not limited to the above-exemplified compounds.
As a material of the continuous phase, a material which is liquid during the capsule preparation process is used. In the case of a microcapsule containing core material dispersed in a hydrophobic continuous phase or non-aqueous continuous phase, examples of materials of the continuous phase include higher fatty acids, hydrocarbons, organic solvents, esters, silicones, higher alcohols, animal and vegetable oils and the like, which are exemplified as the core materials. One or more materials among them are used for the materials of the continuous phase. Among organic solvents, even a material having a boiling point lower than that of water may also be used providing it can expel water from the system azeotropically.
In preparation of emulsion, when a particle is prepared of which particle size is essentially from 0.3 to 100 xcexcm and the median particle size is in the range from 1 to 20 xcexcm in a 2-liter round bottom cylindrical glass reaction vessel having an internal diameter of 12 cm equipped with a mechanical stirrer, it is preferable that the reaction solution is stirred at a speed from 50 to 1000 rpm, particularly from 300 to 1000 rpm.
In preparation of emulsion, when a reaction solution is stirred by a mechanical stirrer and then a particle is prepared, of which the particle size is essentially from 0.1 to 30 xcexcm and the median particle size is from 0.5 to 5 xcexcm by a homomixer, it is preferable that the reaction solution is treated by the homomixer at a speed of from 1000 to 20000 rpm, particularly from 5000 to 10000 rpm.
In preparation of emulsion, when a reaction solution is stirred by a mechanical stirrer, treated by a homomixer and then a particle is prepared, of which the particle size is essentially from about 0.1 to 1 xcexcm and the median particle size is from about 0.2 to 0.8 xcexcm by a microfluidizer, it is also preferable that the reaction solution is treated by the microfluidizer at a speed of from about 300 to 5000 kg/cm2.
One object of the treatment by a homomixer and microfluidizer is to decrease the particle size. Another object is to produce a microcapsule containing core material wherein the capsule wall is not decomposed when shearing strength generated in this treatment is applied.
The treatment by a homomixer or a microfluidizer may be repeated two times or more to decrease the particle size more. When ultraviolet ray absorber is used as a core material, repeating the treatment by a homomixer or a microfluidizer often has another effect which decreases the amount of free ultraviolet ray absorber in the dispersion.
The preparation of emulsion in the presence of alcohol, particularly polyhydric alcohol such as ethylene glycol, polyethylene glycol, glycerin or the like, may be conducted in order to decrease the particle size more. When ultraviolet ray absorber is used as a core material, this method often has another effect which decreases the amount of free ultraviolet ray absorber in the dispersion.
The preparation of emulsion in ultrasonic wave may also be conducted in order to decrease the particle size more.
Next, surface treatment of a microcapsule containing core material by the compound (A) during production will be described below.
A microcapsule containing core material can be produced even if the surface treatment by the compound (A) during production of a microcapsule containing core material is not conducted. However, according to the production method of the present invention, it is guessed that a silanol group which did not participate in condensation remains on the surface of an uncured capsule immediately after emulsification. Therefore, a surface treatment with the compound (A) is preferably conducted to prevent coagulation of a microcapsule containing core material.
When the compound (A) for surface treatment is a compound which is easily hydrolyzed in water such as a chlorosilane including trimethylchlorosilane and hexamethylsilazane, it is preferable that this compound (A) is added to the emulsion solution after emulsification and then, the solution is neutralized.
When the compound (A) for surface treatment is an alkoxysilane like trimethlethoxysilane, it is necessary that following emulsification, this neutral solution is made somewhat acidic or basic and the alkoxysilane is hydrolyzed once. Also when a compound (A) carrying a silanol group from the beginning is used as it is for surface treatment, it is necessary that following emulsification, this neutral solution is made somewhat acidic or basic. Then, the compound (A) is fixed on the surface of a capsule by neutralization. The control of pH should be conducted carefully so that the capsule is not decomposed. In the case of treatment at an acidic pH, the pH is preferably from about 3 to 6.5. In the case of treatment at a basic pH, the pH is preferably from about 7.5 to 10. Examples of the compound (A) used in this surface treatment will be described below, however, it is not limited to the exemplified compounds.
One object of the surface treatment is to prevent coagulation of a microcapsule containing core material. It is preferable to add, after preparation of emulsion, a compound (A) carrying 3 alkyl groups on a silicon atom such as trimethylchlorosilane, ethoxytrimethylsilane, t-butyldimethylchlorosilane, hexamethyldisiloxane, hexamethyldisilazane and the like, to prevent coagulation of a microcapsule containing core material.
Further, after preparation of emulsion, a compound (A) carrying a cationic group as an organic substituent such as octadecyldimethyl-(3-trimethoxysilylpropyl)ammonium chloride can be added, hydrolyzed and neutralized to make the surface of a microcapsule containing core material cationic.
Further, it is possible, after preparation of emulsion, to variously modify the properties of the surface of a microcapsule containing core material and to obtain various functions by controlling pH to neutralize a compound (A) such as methyldiethoxysilane, methyldichlorosilane, tetramethoxysilane, tetraethoxysilane, tetrachlorosilane, methyltrimethoxysilane, methyltriethoxysilane, methyltrichlorosilane, dimethyldimethoxysilane, dimethyldiethoxysilane, dimethyldichlorosilane, octamethylcyclotetrasiloxane, phenyltrimethoxysilane, phenyltriethoxysilane, phenyltrichlorosilane, diphenyldimethoxysilane, diphenyldiethoxysilane, diphenyldichlorosilane, hexyltrimethoxysilane, octyltriethoxysilane, decyltrimethoxysilane, stearoxypropyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris-(xcex2-methoxyethoxy)silanevinyltrichlorosilane, xcex3-methacryloxypropylmethyldimethoxysilane, xcex3-methacryloxypropyltrimethoxysilane, xcex3-methacryloxypropylmethyldiethoxysilane, xcex3-methacryloxypropyltriethoxysilane, xcex3-chloropropyltrimethoxysilane, xcex3-mercaptopropyltrimethoxysilane, xcex3-isocyanatepropyltriethoxysilane, 3-triethoxysilylpropylsuccinic anhydride, octadecyldimethyl-(3-trimethoxysilylpropyl)ammonium chloride, dimethylhexadecyl-(3-trimethoxysilylpropyl)ammonium chloride, methoxy(ethoxy)n(propoxy)mpropylmethyldialkoxysilane, methoxy(ethoxy)n(propoxy)mpropyltrialkoxysilane, a compound (A) derived from xcex3-glycidoxypropyltriethoxysilane, xcex3-glycidoxypropylmethyldiethoxysilane and another substance, such as N-[2-hydroxy-3-(3xe2x80x2-trihydroxysilyl)propoxy]propyl hydrolyzed protein and N-[2-hydroxy-3-(3xe2x80x2-dihydroxymethylsilyl)propoxy]propyl hydrolyzed protein, a compound (A) derived from a silane coupling agent such as xcex2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, xcex3-[N-(xcex2-aminoethyl)amino]propylmethyldimethoxysilane, xcex3-[N-(xcex2-aminoethyl)amino]propyltrimethoxysilane, xcex3-[N-(xcex2-aminoethyl)amino]propyltriethoxysilane, xcex3-aminopropyltrimethoxysilane, xcex3-aminopropyltriethoxysilane, xcex3-(N-phenylamino)propyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris-(xcex2-methoxyethoxy)silanevinyltrichlotosilane, xcex3-methacryloxypropylmethyldimethoxysilane, xcex3-methacryloxypropyltrimethoxysilane, xcex3-methacryloxypropylmethyldiethoxysilene, xcex3-methacryloxypropyltriethoxysilane, xcex3-chloropropyltrimethoxysilane, xcex3-mercaptopropyltrimethoxysilene, xcex3-isocyanatepropyltriethoxysilane, 3-triethoxysilylpropylsuccinic anhydride and other substance.
The above-described series of surface treatments may be combined.
In the curing treatment of the instant invention, the strength of a wall of a microcapsule containing core material can be increased by further progressing the polycondensation reaction by removal of alcohol generated in hydrolysis of an alkoxysilane, which is a kind of the compound (A), or by dehydration due to the lapse of time or by heating and removal of water out of the reaction system, and the like. The temperature of the reaction solution is preferably 30xc2x0 C. or more. Heating at the boiling point of water in the reaction system is particularly preferable, although the boiling point may be changed by control of pressure. The above-described dehydration due to the lapse of time occurs since the siloxane condensation naturally progresses at neutral pH. The removal of water out of the system means for example distilling off (condensed water obtained by cooling of solvent vapor is removed out of the reaction system without returning it to the reaction system) and the like.
In thus obtained microcapsule containing core material, it is preferable that the weight of the core material is from about 0.01 to 99% by weight based on the weight of the microcapsule containing core material. This ratio of the weight of the core material to the weight of the microcapsule containing core material is hereinafter referred to xe2x80x9ccore weight ratioxe2x80x9d. According to the present invention, a wide range of the core weight ratio can be obtained, the thickness of the capsule wall is easily controlled by correlating the core weight ratio with the particle size.
The microcapsule containing core material has sufficient water resistance when it is used at a pH around neutral.
The strength of the capsule depends on the kind of the compound (A) used, particle size, curing conditions, and core weight ratio. As an example, in the case of a microcapsule produced for cosmetics having a particle size of 1 to 2 xcexcm and a core weight ratio of 90%, even if it was compounded in a cosmetic via mechanical mixing process and applied on skin, no decomposition was recognized.
The microcapsule containing core material produced according to the present invention can be treated by freeze-drying and spray-drying to be made into a powder.
The intake ratio of a core material into a microcapsule containing core material produced according to the present invention is from about 50 to 99.9% on a weight to weight basis, and in preferable cases, from about 80 to 98% on a weight to weight basis. This intake ratio shows how much % of a core material added is incorporated in the capsule.
Though the microcapsule produced according to the above-explained method exerts an excellent effect, incorporation of a core material into the capsule is not necessarily complete. A part of the core material may remain in the continuous phase, and may continuously leak out of the capsule into continuous phase with the lapse of time.
When a part of the core material remains in the continuous phase, and continuously leaks out of the capsule into the continuous phase with the lapse of time, various undesirable problems may occur.
For example, an object of preventing contact of the core material with skin, which is suggested in cosmetic fields and the like, can not be attained when the core material remains in the continuous phase or leaks into the continuous phase. Further, although it is suggested that an unstable material which is unstable and discolors with the lapse of time when exposed to outer atmosphere is incorporated into a microcapsule for insulation from the atmosphere and prevention of discoloring with the lapse of time, the object of the invention can not fully be accomplished if incorporation of the core material into the capsule is not complete.
In addition to the object mentioned above, there is another object of the present invention, which is to provide a microcapsule having a capsule wall made of a specific organopolysiloxane and a method for producing the same in which the amount of a core material that has not been incorporated into a capsule is minimum, and leaking of the core material out of the capsule in later use is minimum.
That is, the present invention provides a microcapsule containing core material wherein the capsule wall is made of organopolysiloxane synthesized by polycondensation of a compound (B), wherein at least one compound selected from the group consisting of hydrolyzable silanes and hydrolyzable polysiloxanes is added to the core material.
The present invention further provides a microcapsule containing core material wherein the capsule wall is made of organopolysiloxane synthesized by polycondensation of a compound (B), and the surface of the formed capsule wall is treated at least once with a hydrolysate of at least one compound selected from the group consisting of hydrolyzable silanes and hydrolyzable polysiloxanes.
The present invention further provides a method for producing a microcapsule containing core material, comprising a step wherein at least one compound selected from the group consisting of hydrolyzable silanes and hydrolyzable polysiloxanes is added to a core material, and a step wherein a compound (B) is polycondensed to synthesize organopolysiloxane to form a capsule wall.
The present invention further provides a method for producing a microcapsule containing core material, comprising a step wherein a compound (B) is polycondensed to synthesize organopolysiloxane to form a capsule wall, and a step wherein the surface of the formed capsule wall is treated at least once with a hydrolysate of at least one compound selected from the group consisting of hydrolyzable silanes and hydrolyzable polysiloxanes.
In the microcapsule containing core material of the present invention, at least one compound selected from the group consisting of hydrolyzable silanes and hydrolyzable polysiloxanes is added to a core material, or the surface of the formed capsule wall is treated at least once with a hydrolysate of at least one compound selected from the group consisting of hydrolyzable silanes and hydrolyzable polysiloxanes, so that the amount of the core material which has not been incorporated into the capsule is minimum, or leaking out of the core material of the capsule in later use is minimum.
Herein, the term xe2x80x9chydrolyzable silanesxe2x80x9d and xe2x80x9chydrolyzable polysiloxanesxe2x80x9d respectively mean silanes and polysiloxanes which generate a silanol group by being hydrolyzed. As the hydrolyzable silanes and hydrolyzable polysiloxanes to be added to a core material or to be used for the treatment of the surface of the formed capsule wall, methyltrichlorosilane, methyldichlorosilane, dimetyldichlorosilane, trimethylchlorosilane, phenyltrichlorosilane, diphenyldichlorosilane, methyltrimethoxysilane, methyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, hexyltrimethoxysilane, octyltriethoxysilane, decyltrimethoxysilane, tetramethoxysilane, tetraethoxysilane and Me3SiO(Me2SiO)f[MeZSio]gSiMe3(f represents an integer from 5 to 50, and g represents an integer from 2 to 100 and Z represents hydrogen or an alkoxy group) are exemplified. Particularly preferable examples thereof include tetramethoxysilane, tetraethoxysilane, methyltrichlorosilane, Me3SiO(Me2SiO)f[MeZSiO]gSiMe3(f represents an integer from 5 to 50, and g represents an integer from 2 to 100, f/g=0.1 to 20, weight-average molecular weight (M.W.)=200 to 10000, and Z represents hydrogen, a methoxy group or ethoxy group) and the like.
At least one compound selected from the group consisting of hydrolyzable silanes and hydrolyzable polysiloxanes is usually added to a core material previously, and added to the continuous phase together with the core material.
The treatment of the surface of the formed capsule wall with a hydrolysate of at least one compound selected from the group consisting of hydrolyzable silanes and hydrolyzable polysiloxanes (hereinafter, referred to as over coat treatment) is conducted at least once. It is conducted after mixing and emulsification, and usually before surface treatment of the capsule wall with a compound (A) and the like, namely, prevention of coagulation and curing treatment of the capsule wall. This over coat treatment is usually conducted by adding to the continuous phase at least one compound selected from the group consisting of hydrolyzable silanes and hydrolyzable polysiloxanes. The over coat treatment is preferably conducted with stirring at approximately the same temperature as that in the mixing and emulsification. The amount added of at least one compound selected from the group consisting of hydrolyzable silanes and hydrolyzable polysiloxanes is from 0.1 to 30 mol, preferably from 0.5 to 10 mol per 100 of the total mol number of Si used for formation of the capsule wall.
If the intake ratio is not sufficiently high, purification such as removal of a core material which has not been incorporated in, and the like is usually required. Examples of the purification methods are as follows.
One purification method is that in which a liquid phase not dispersing the capsule and unmixable with the other liquid phase dispersing a capsule is added, said two liquid phases are mixed completely, then both liquids are separated by decantation or by liquid separation, after separation of the two phases, to transfer impurities to other liquid phase. When both liquid phases are not easily separated, centrifugal separation may be adopted. Further, when both liquid phases are not easily separated, liquid which is miscible with the liquid phase dispersing a capsule may be further added to wash and separate the capsule.
Another purification method is that in which a microcapsule containing core material precipitated or floated by centrifugal separation is collected portion-wise. In this case, after the above-described procedure, impurities are removed together with a solvent. The collected microcapsule is re-dispersed into a solvent which can disperse the capsule. This procedure is repeated.
There is a method by ultrafiltration as another purification method. In this purification method by ultrafiltration, impurities eluted by ultrafiltration are removed, and the concentrated microcapsule is re-dispersed into a solvent which can disperse a microcapsule containing core material. This procedure is repeated.
The microcapsule containing core material of the present invention is bio-inactive, and the capsule wall thereof has thermal and mechanical stability and light resistance which are general basic properties of an organopolysiloxane. The present invention is advantageous also in the point of cost since a microcapsule containing core material can be produced directly from a compound (A) such as analkoxysilane, halogenated silane, hydrogensilane, polysiloxane and the like. In addition, a wide range of microcapsules containing a core material can be easily designed according to various objects by combining various compounds (A).
The microcapsule containing core material of the present invention having such various properties can be widely applied to pharmaceuticals, liquid crystal, chemical products, recording materials, cosmetics, aromatics, enzymes, agriculture, adhesives, fiber, foods, catalysts, detergents, coloring matters, paints, preservatives, solvents and the like.
For example, when a microcapsule containing core material of the present invention using a ultraviolet ray absorber as the core material is applied to cosmetics, the following merits are obtained as compared with the case in which a ultraviolet ray absorber itself is compounded in cosmetics.
1. Safety of cosmetics increases since permeation of a ultraviolet ray absorber into skin decreases.
2. A more stable formulation becomes possible in formulation systems in which stable formulations are conventionally difficult.
3. When a ultraviolet ray absorber itself is compounded in cosmetics, addition of a stabilizer may be required for preventing yellowing of the ultraviolet ray absorber. However, there is no necessity of a stabilizer in this invention.
4. When an ultraviolet ray absorber such as ethylhexylmethoxycinnamic acid or the like is compounded itself, tackiness and the like occur, and when an ultraviolet ray absorber such as methoxybutylbenzoylmethane or the like is compounded itself, a crystal is deposited to cause roughness. However, in this invention, these problems are solved, and the use feeling of the cosmetics is increased. Further, the adhesion of the cosmetics also increases.
5. When an ultraviolet ray absorber itself is compound in a formulation having high water content such as a lotion and the like, it is necessary to add a certain amount of a surfactant. However, according to the present invention, there is no need of addition of a surfactant or only a small amount of a surfactant should be added, therefore, a ultraviolet ray absorber can be easily compounded. Further, methoxybutylbenzoylmethane or the like can not be easily compounded since it manifests poor solubility and the degree of solubility thereof decreases by the influence of other compounding components. In the present invention, however, compounding thereof is easy. Namely, according to the present invention, compatibility with other compounding components (raw material of cosmetics, oil, solvent and the like) increases.
6. Ultraviolet ray absorbing effect (SPF value), namely effect for protecting humane body from a ultraviolet ray, increases.
When a microcapsule containing an ultraviolet ray absorber as the core material is applied to cosmetics, the particle size of the microcapsule is preferably from 0.05 xcexcm to 50 xcexcm, more preferably from 0.3 xcexcm to 30 xcexcm, and the compounding amount (by weight) of the ultraviolet ray absorber is preferably from 0.1% to 50%, more preferably from 0.5% to 30%, based on the amount of the microcapsule.
When the microcapsule containing core material of the present invention is used for pharmaceuticals, cosmetics, coloring matters and the like, following ingredients, for example, are cooperatively used with the microcapsule:
fatty acids particularly higher fatty acid, hydrocarbons, organic solvents, esters, phenols, silicones, silanes, metal alkoxides, alcohols particularly higher alcohol, animal and vegetable oils, extracted components, electrodonative coloration organic compounds, coloring matters, ultraviolet ray absorbers, vitamins, effective drug components, aroma components, preservative, sterilizer, salts; amino acid and its derivatives, protein, hydrolyzed protein and its derivatives, saccharides, polysaccharide, enzymes, fluorocarbon-like substances, and the like, which are exemplified as the core material in the above paragraphs; and
surfactants classified into anionic, cationic, nonionic, and amphoteric surfactants and the like which includes betaine type surfactant fatty acid salt, fatty acid hydrolyzed protein condensate, sulfate type surfactant, phosphate type surfactant, polyester and its derivatives.